


A Bird Set Free

by hrhjtinajv



Category: Shadowhunters (TV)
Genre: Alec hates magnus at first, Angst, Doctor!Magnus, Enemies to Friends to Lovers, F/M, Human AU, I am so sorry, Lightwood Siblings, M/M, Magnus Bane & Isabelle Lightwood Friendship, Matchmaker Isabelle Lightwood, Protective Alec Lightwood, Sick!Izzy, like a lot, worried!alec
Language: English
Status: In-Progress
Published: 2017-03-31
Updated: 2017-04-01
Packaged: 2018-10-13 05:25:00
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 8,945
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10507161
Author URL: https://archiveofourown.org/users/hrhjtinajv/pseuds/hrhjtinajv
Summary: Isabelle is hiding something from Alec. Something big. Life-or-Death big. Magnus is Isabelle's doctor and Alec hates him.Things progress from there.





	1. Chapter 1

**Author's Note:**

> Hiya loves~  
> So, I would like to go on record and say that Isabelle Lightwood is my favorite character and I love her very much and I don't want to hurt her, but this story just had to be written, sorry!!!  
> The title is taken from the song "Bird" by Billie Marten because I feel like it SUCH an Izzy song.  
> The funny thing is, this was supposed to be humor prompt, but my dumbass decided to create an angst monster out of it - you've been warned.  
> Honestly, this is more Lightwood siblings-centric in the beginning, but it definitely ends with a lot of Malec, so for those of you reading for Malec, just tough it out the first few chapters - you won't be disappointed!  
> Yell at me on tumblr: unorthodoxpartofyourworld

 

Alec Lightwood was not as oblivious as people thought he was. He noticed things, he just didn’t always know what to do about them. In his experience, he’d end up finding out in a matter of time either way, so he generally just let things happen. 

For example, he’d noticed when Jace had started going out more and honest to god  _ giggling _ at his phone. He knew that Jace was seeing someone who’d actually had him hooked, and sure enough, after a few months, Jace brought home his new girlfriend, Clary Fray. She was nice and she made Jace happy, so Alec shrugged his shoulders and congratulated the pair. 

He’d noticed when Lydia stopped eating and started skipping their weekly hangouts to stay late at the office. While everyone else got worried, Alec simply ordered takeout, took it to her office one night, and sat in the corner with his laptop, finishing up his own paperwork. Later that night, Lydia explained about the office-wide cuts they were making and the quarterly review coming up. Alec told her that he understood, but made her promise to eat and stay healthy. He assured her that they couldn’t afford to lose a sharp, cut-throat business woman, and he was right. Lydia was promoted instead. 

He’d noticed right off the bat when Simon’s eyes rested a little too long on his little sister. He’d noticed the blush that colored his cheeks when she said his name and the way his jaw tightened when Isabelle mentioned whatever guy she was currently seeing. Alec had been hesitant at first, but the more he got to know Simon, the more he thought that maybe this nerdy lil guy would be good for his sister. He had yet to see if he was right on that one, but he was patient. 

He’d noticed when Izzy had come home angry and locked herself in her room for hours, refusing to eat. He’d noticed the next day when she emerged fresh-faced, in her baggiest sweats and parked herself on the couch, watching reruns of Friends. He knew that meant boy drama, so he’d popped in a few toaster waffles, spooned mint chocolate chip ice cream over them, drizzled them in syrup, and plopped down next to her. He didn’t say a word; instead, made half-hearted comments about how bone-headed Ross and Rachel were and let her squeal about Chandler and Monica (they were watching The One In Vegas: Part 2). He didn’t say a thing when she skipped to the end of season six to watch The One With The Proposal. Instead, he just put his arm around her as she sniffled softly, kissing the top of her forehead and waiting for her talk about it. 

Sure enough, Meliorn had broken up with her. Alec knew she’d really loved him, but at the moment, he hated the man’s guts. If Meliorn got a couple more speeding tickets than usual, Alec had nothing to do with it. He was just in the right time at the right place. 

Alec knew people. 

It was one of the reasons he was a good cop. He knew how to read people and how to react. He often saved his sleuthing for the job because he expected the truth to come out eventually, and snooping around his loved ones’ business was a waste of of time. 

No one hid anything from him. They didn’t  _ do _ secrets - not important ones. 

That’s probably the reason Alec was scared when he realized Isabelle - his beautiful, loving, caring, amazing, young woman of a sister - was hiding something. Not just from him, from everyone. 

It had started small. Isabelle would get up suddenly and rush to the bathroom, face pale as a sheet. Alec thought it was just period problems, but even he knew that periods didn’t go on all month long. 

Next, Isabelle was making trips without telling anyone. When Alec asked her where she was, she’d just give him her thousand-watt smile and make up some bullshit excuse about getting food or stopping by a friend’s. It had worked the first few times, but Alec could tell that something was up.

Isabelle started spending more time locked up in her room and started wearing heavier makeup. Alec wondered if it was about a boy, but Isabelle wasn’t doing any of the things she’d done before. This behavior was new for her and Alec didn’t know what to do about it. 

He began to worry when he was joking around with Izzy one morning. They were fighting over the last chocolate chip toaster waffle and Izzy had grabbed the box and tried to sprint out of the kitchen. Alec grabbed her by the waist and yanked her back, but he gasped as he felt her usually soft stomach replaced with hard edges. 

“Izzy, what - “ he began, shocked. He lifted up her sweatshirt - that’s another thing, she’d begun wearing baggy clothes  _ everywhere _ \- and his eyes widened how much weight she’d lost. Her ribs were beginning to show and her skin was paler than he’d ever seen before - and Alec had seen her during her goth phase in middle school. 

Izzy twisted away, caught between looking angry and scared. She looked dangerous. 

“Stop it, Alec.” she hissed. “Here, you can have the last fucking waffle.” She threw the box at his head and rushed to her room, locking the door. 

Alec made the waffle and knocked on her door. When there was no answer, he left the waffle at the door, knocked a few more times, and went to his room. As soon as he closed his door, he heard the door click as Izzy’s door opened. 

He smiled. 

After a few hours, he came out of his room, getting ready to go to work. Thanks to a stupid bet that his team had lost with the commander of the other shift, all of them had to work the night shift for a week. Sometimes, it really sucked working in the 99th precinct, but he loved his co-workers regardless. 

When he entered the living room, he found Izzy curled up on the couch. As soon as she saw him, she got up and wrapped her arms around him, burrowing her face in his chest. Alec sighed and wrapped his arms around her, holding her close. 

“You gonna tell me what’s going on, Iz?” he asked, carefully. 

“It’s nothing, big brother. I’m just stressed.” she replied slowly, as if she was choosing her words precisely. 

“Izzy, this isn’t nothing. If something’s going on, i-if you’re going through something, I have to know. Isabelle, I’m your older brother. If I’m not there for you, what good am I?” Alec pushed her away a bit, just to grab her chin and make her look into his eyes, desperate and pleading. 

“I know, Alec.” Isabelle smiled, but it wasn’t her normal, thousand-watt smile. It was dimmer, weaker, and her face didn’t glow anymore - it was ashy and gray. “I love you so much, big brother. You gotta know that.” 

Alec wanted to push, but he didn’t. Instead, he planted a kiss on Isabelle’s forehead and squeezed her one last time before gathering his things and rushing to work. 

It continued with Isabelle suddenly asking to take over her health insurance account. Alec usually oversaw all of their expenses in a large joint account, but suddenly, Isabelle was asking to make hers independent and private. 

“I’m 22 now, Alec! I can manage my own insurance.” she declared stubbornly. 

“Fuck that, there’s something else going on, isn’t there? Why are you doing this so suddenly, with zero warning?” Alec argued, in shock. 

“Are you kidding? What do you mean zero warning? Have you forgotten what our mother says every time she sees us? ‘Alec, darling, it’s nice to see you doing so well. Isabelle, straighten up. You should start taking more responsibility.’ I’m just trying to  _ appease _ our  _ mother. _ ” Izzy seethed. 

“No, no way! Don’t let our mother get to you! This is ridiculous! Fuck, I’m calling mom right now, I don’t know what’s going on with you, but this is suspicious, Iz,” Alec whipped his phone out, ready to dial his mother and settle this ridiculous feud she had with Isabelle, but he stopped when he saw the look on Izzy’s face. 

“Alec, please, big brother.” she pleaded, her eyes wide and arms wrapped around her small, frail body.  _ When did Isabelle become...frail? _ Alec wondered. He ran a hand over his tired face and groaned.

“Izzy, please. I need you to talk to me.” he sat down and gestured for Isabelle to do the same. She sat down gingerly next to him and took his hand in hers. 

“Alec, this is just something I need to do. Can you please just trust me? I don’t want to… this is just something I have to do.” she implored, clutching his hand like a lifeline. 

Alec didn’t want to. He knew that something was going on in his sister’s life and it killed him that she wasn’t telling him. Izzy was usually always open about everything going on in her life, Alec couldn’t imagine what she could be hiding. A part of him wanted to believe her - that this was just her way of getting back at their mother - but there was something off about the entire situation, something he just couldn’t put his finger on. 

He let out a disgruntled, defeated sigh and logged onto his computer, unlinking Isabelle Lightwood’s account from his own. 

He felt something break inside him

  
  


  
  



	2. Chapter 2

**Summary for the Chapter:**

> The Lightwoods have a family dinner and one very handsome freewheelin' bisexual makes an appearance.

Reality came crashing down on him two months after he’d unlinked Isabelle’s account from his own. 

In that time, Isabelle had gotten worse. Alec wasn’t sure if she was depressed, suffering an eating disorder, or if she was just feeling down. This  _ thing _ \- whatever it was - had been going on for almost eight months now and he was getting increasingly worried, but he didn’t know what to do. 

Alec didn’t understand what was happening, but he bit his tongue because every time he questioned Isabelle, she’d clam up and get angry. At first, he’d backed off immediately, but he was reaching the end of his rope. He wanted to know what was going on with his sister. 

He angrily pulled his shirt on, grumbling as he heard Izzy getting dressed in her room. They were getting ready for a dinner with their parents. Jace had moved in with Clary a few months ago, so he promised to meet them outside the restaurant so they could walk in together. They still had about 45 minutes, but Alec didn’t want to take any chances. 

Robert and Maryse Lightwood were strict and held their children to impossibly high standards. They were the hardest on Isabelle, which is why Alec didn’t want to waste any time. The blame would somehow get put on her, and with everything going on -  _ whatever was going on _ \- Alec knew that Isabelle didn’t need the wrath of Maryse Lightwood added on top. 

He was going to sit Isabelle down and  _ interrogate _ her tonight, damn it. He couldn’t deal with the secrecy any longer, especially when whatever was going on clearly had a bad effect on Izzy. 

He yanked his nice dress shoes on and raked his fingers through his hair, making even less of an effort than usual, and marched over to Isabelle’s room, barely stopping himself from pounding on the door. 

After a few moments, Izzy stepped out and Alec stared at her. 

She looked gorgeous, as usual, but there was something off. Her makeup was done immaculately, but it was thick on her face instead of looking flawless and natural like it usually did. Her face looked painted on. Her hair was pulled into a tight bun, but Alec could tell that it was thinner than usual. She was wearing a long-sleeved navy blue knit dress that fell to her mid-calf and black heels. But, the dress didn’t look like it fit her properly. Instead of hugging her curves, it sat loosely at her waist and hung over her hips instead of clinging to them. Alec had seen this dress before - hell, he was the one who was dragged along to buy it - he knew how it was supposed to look on her. 

The biggest shock was her heels. Instead of the usual stunning pumps, she was wearing  _ wedges _ \- small, one-inch wedges. They were stylish - thin black strips of leather crisscrossing over her feet and up her ankles, stopping just an inch short of her dress. 

She didn’t look  _ bad _ **_,_ ** she just didn’t look like herself. 

“Izzy, you look… beautiful, as always.” Alec began, following her to the living room and grabbing her jacket before she could. “It’s just… h-have you lost weight? You don’t fill that dress out the way you usually do.” Alec finished anxiously as he helped her into her coat. He didn’t want her to feel uncomfortable or hurt, but he couldn’t just not address the problem. 

He’d already made that mistake once, when he let six months go by before he said a thing. 

“I’m fine, Alec. Things have just been busy. Don’t worry about it, brother.” she brushed off, straightening the lapels on his jacket before turning to open the door. “Wait,” she turned her head over her shoulder. “Lights?”

“Off.” he replied. 

“Phone?”

“Check.”

“Keys?”

“Yep.”

“Wallet?”

“We’re good.”

“Alright, let’s move.” Izzy opened the door and stepped out of their small apartment. Alec followed, locked the door, and took Izzy’s hand, looping her arm through his. 

If she wasn’t going to tell him what was going on, he could be a supportive brother from the sideline, he decided. 

\---

The train ride was uneventful. Alec pulled out his phone and gave one earbud to Izzy. He tried to be passive-aggressive in his music choice, but he wasn’t sure if Izzy caught on. 

He played “Stand By You”, “Lean On Me”, and even reached deep into his playlist and pulled out the original “We Are Family” by Sister Sledge. When the opening notes came on, Isabelle turned to him with an incredulous smile. 

“I didn’t know you still have this!” she whisper-exclaimed, grinning up at him excitedly. Honestly, it was one of the first real smiles he’d seen in awhile and Alec’s heart warmed at the sight of it. Isabelle pursed her lips together and closed her eyes, lolling her head back dramatically and moving her hands in a circular motion. Alec loved that about her - that she could just start dancing on the subway and not give a fuck about who saw. 

Alec leaned his head back and watched his little sister. She was amazing. He wondered if it was something he did, something that upset her or made her not trust him anymore. 

He really hoped that wasn’t the case. 

When they finally reached their stop, both Alec and Isabelle were in a considerably better mood, laughing and singing obnoxiously - well, Isabelle sang, Alec just laughed - all the way to the restaurant. 

\---

Jace heard them before he saw them. Looking around for the loud, off-key singing, he spotted his two adopted siblings and grinned, walking over to join them. Isabelle was halfway through a fierce rendition of ‘Bills, Bills, Bills’ by Destiny’s Child, so Jace - obviously - linked his arm through hers and joined in. 

_ We probably look like idiots _ , he thought, observing the three of them. A tall, brooding giant doubled over in giggles, a handsome, blond devil belting out every high note he came across, and a ridiculously short, gorgeous girl between them, singing off-key like she was in the shower. 

When they reached the front of the restaurant, Izzy let go of both of her brothers’ arms and spun, hitting the last note while shaking her hips. 

Jace and Alec laughed at her grand finish, so Jace almost didn’t catch the heaving breaths she was taking. He wanted to brush it off, but he’d noticed something off about Izzy lately. 

He hadn’t noticed anything until Alec had come over a few months ago, right after he’d moved in with Clary, and asked if he’d noticed anything off about Isabelle.

“I don’t know, Alec, she seems fine to me.” he shrugged. With Izzy, it was probably a guy thing and she’d tell them eventually so he’d know who to punch in the face. 

He didn’t think about it again until Clary mentioned it a few weeks later. 

“So, I hung out with Isabelle today.” she called as she was putting some groceries away. 

“Sounds like fun. What’d you do?” Jace asked, only half-listening, really. 

“Not much, actually. We were going to go shopping but she had an appointment or something and had to cut it short. We just ended up going to a coffee shop and talking for a bit. It was nice…” Clary trailed off. 

“That’s nice, babe.” Jace remarked, absently flipping through the channels on the TV. 

“It’s just… Jace!” Clary stepped out of the kitchen, hands on her hips. 

“Wh-What? I’m listening!” he protested, turning around on the couch. Clary rolled her eyes.

“No, I mean,” Clary came to sit in front of him, arms crossed anxiously across her chest. “Is Izzy okay? I mean, if something’s going on, you should tell me. I’m worried about her, something just doesn’t feel right.” 

Jace remembered what Alec had said when he came over, stoic, yet somehow still panicked, asking if he’d noticed anything off with Izzy. 

“I-I don’t know.” Jace replied honestly.

That had been almost three months ago and Jace could now definitely tell that something was not right with Izzy. It wasn’t just in the way she acted either, physically, she looked different. 

He wondered if she was....sick. 

_ No way, _ Jace scoffed to himself.  _ Izzy’s one of the most health conscious people I know. And even if she was sick, of course she’d tell us. She would never hide something like that. _

Jace took another look at Izzy’s small, thin frame. 

_ Would she? _

\---

Alec exhaled as they walked into the restaurant. Jace went first, of course, since he was somehow their favorite - or, at least, the one their parents criticized the least. Alec followed him, a slight hunch in shoulders. Isabelle came last, her head held high and proud. She had a fierce look in her eyes. 

That was another thing Alec loved about her - she refused to let anyone put her down. 

When they got to the table, Maryse and Robert stood up to greet them. Maryse pointedly did  _ not _ give Izzy a hug - which Alec had noticed before, but this time he got angry. Biting down on his tongue, he kissed his mother’s cheek and pulled back as quick as possible, his eyes gleaming with frustration. Alec pulled out Isabelle’s chair out for her before he sat down and Jace got up to push it in for her. 

Isabelle turned and looked at her brother’s in surprise, raising her eyebrows, but shrugged, turning back to their parents. 

“I see you’ve decided to dress more appropriately tonight, Isabelle.” Maryse began, twirling her wine glass between her fingers. 

“You look lovely, dear.” Robert added. Maryse just pursed her lips and waited for Isabelle’s response.

“Thank you, mother, father. I tried today.” Izzy looked like she was forcing the words out and Alec couldn’t blame her. 

“Perhaps you should try more often.” Maryse sniped. Alec gritted his teeth, Jace shifted uncomfortably, but Isabelle just lifted her chin and looked her mother square in the face. 

“Perhaps what I wear doesn’t concern you anymore, mother.” Isabelle responded coolly. She cleared her throat and lifted her own glass, taking a long sip of wine. 

Maryse stared at her a moment before she jumped in again, ready to attack. “Isabelle, stop thinking that I’m always attacking you. You are my daughter and you will always be my daughter. I expect my daughter to look decent and modest, that is all. Dress well, Isabelle, and I won’t say anything about it.” she huffed.

“But you see, mother, I did dress well today. But you still made a comment. I don't understand what you expect me to do.” Izzy pushed her hair back and straightened her shoulder even more, looking regal and fierce, with determination that Alec hadn't seen before. 

“I expect you to stop talking back and eat your food.” Maryse sighed, eyeing Isabelle critically. “So, what else has been going on, children? Alec? Jace?” Maryse inquired. 

Alec and Jace both looked any each other, then at Isabelle, and back at each other. They didn't know  _ what _ to say. Jace cleared his throat and launched into some story about work while Alec debated on whether telling his parents about Isabelle’s…  _ situation _ would be a bad idea or not. It seemed like it might be their only option. 

Alec hastily excused himself to go to the restroom, stomach churning as he wondered how Izzy would react to being put on the spot like that. He knew that she would never pull something like that on him, but he didn't feel like he had any other options.

In the bathroom, Alec splashed water in his face, emotions swirling through his head - anger, fear, frustration, anxiety, but most of all, sadness. Something was going on with Isabelle - had been going on for months - and she didn’t want to tell him. She didn’t trust him. 

Alec had come to a decision. He needed to confront this issue right now, even if it meant involving their parents.

This was the internal debate swirling through Alec's mind when he almost bowled over another person. 

Alec caught himself at the last second, arms going around the waist of the man he’d knocked over to steady him, and looked at the man he'd collided with.

His breath caught for a moment and he briefly forgot why he was so worried. 

The man in front of him was gorgeous, bronzed sun-kissed skin, jet black hair frosted a chestnut blonde color at the tips,  _ well  _ built, and stylish. He was wearing a deep purple shirt tucked into slim fit black slacks. His fingers were clad with rings and his nails were painted black. 

He looked shocked for a second, hands gripping Alec’s biceps to steady himself. When he straightened and composed himself, there was a mischievous glint in his eyes. 

“Well, hello there, handsome.” the man smiled at him. Alec’s mouth stopped working, just staring at the beautiful man in front of him. The man ran his hands down Alec’s biceps and squeezed before letting go. “What’s your name, darling?” he all but purred. 

“Um, Alec. Alec Lightwood.” he stammered back. Alec knew he had to get back to his table, back to Izzy and his family, but there was something about this man that captivated him. He couldn’t seem to lift his feet.

“I’m Magnus Bane, it’s so nice to-” the man began, but cut himself off, brow furrowing as he stared at Alec with a different kind of scrutiny. “Lightwood?” he asked. 

“Um, yeah.” Alec suddenly snapped out of his stupor and realized that this was not the time, or the place. “Excuse me.” he said as he let go of the man and stepped around him, heading back to the table. 

_ Magnus, _ he thought. 

When he got back to the table, he took his seat and listened to his father finish up a story from the Institute, the office where both his parents worked. When he was done, Alec cleared his throat and reached over to take Izzy’s hand. Izzy looked over at him, confused, but turned her hand upwards and squeezed, giving him support nonetheless. 

Alec’s stomach squelched. Izzy was giving him support even though he was about to put her on the spot in front of their parents. 

Maybe this plan wasn’t the best one. 

Just as he was about to speak, a melodious voice came from behind him. 

“Ah, I’d heard that there was a Lightwood in the restaurant. I just didn’t think I’d get the pleasure of seeing my favorite one tonight.” said the voice, and Alec turned to come face to face with Magnus Bane, the man from earlier. Confusion clouded his face -  _ he didn’t even know the guy _ \- but realized that the warm look in Magnus’ eyes was not directed at him. 

Isabelle’s face looked fear-stricken for a moment, but she covered it up with a - clearly fake and well-practiced - smile. 

“Magnus!” she stood up shakily to give the man a hug. He wrapped his arms around her and whispered something in her ear. She just nodded and turned back to the table. “Mom, Dad, Alec, Jace, this is Magnus. He’s, uh, a friend of mine.” 

Magnus raised an eyebrow at her and pressed his lips into a thin line, but didn’t interrupt. 

“Magnus,” she said, turning back to face him. “This is my family. My mother, Maryse, my father, Robert, and my two brothers, Alec and Jace.”

“Your entire family is as beautiful as you are, Isabelle. It’s lovely to meet you all.” he smiled warmly. “But, didn’t you tell me about a younger brother?” he asked. 

“Ah yes, my little brother, Max. He’s off at boarding school. We all went to the same boarding school when we were younger, it’s up in Itasca. We try to visit once a month since it’s pretty close.” she explained. 

Magnus nodded, exchanged greetings with the rest of the family. His eyes lingered on Alec, making him feel all sorts of things that he didn’t want to address right now. He leaned in and whispered something to Izzy, peaking Alec’s interest again, and went back to his own table. 

When Izzy sat down, she smiled and explained that she’d met Magnus through some mutual friends. 

“We’re  _ just friends _ , Mom.” Izzy groaned, when Maryse began her interrogation. “Plus, I know for a fact that he’s definitely not interested in me anyway.” she said nonchalantly, shooting Alec a playful look. 

Alec hoped that his blush didn’t show, but when Izzy hid her giggle behind her glass, he knew he had failed. 

\---

The rest of the evening progressed as usual, stories being exchanged, discussions of work and school, respectively, and the dreaded inquiry into their personal lives. 

“So, Alec,” his father began, clearing his throat. Alec knew that tone of voice and he closed his eyes, sighing. “Are you seeing anyone?”

There it was. 

Alec wasn’t ashamed of sexuality, but it was awkward when his parents asked, because as much as they tried, they’d always looked down on him and his past relationships with disdain. It was probably part of the reason he hadn’t been able to really hold a steady relationship in the past. 

“Um, no. Work has been heavy. I’ve been focused on that.” he replied honestly. 

Seemingly satisfied, Robert turned to Izzy. 

“And you, Izzy? Are you seeing anyone?”

Alec turned to look at Izzy, who was frozen. Well, not really frozen, per se, but her face had lost all expression, one side of her face sagging while the other twitched. She was breathing quickly, chest heaving with effort. 

“‘Isabelle, what’s wrong?” their mother demanded, sharply. 

Izzy shook her head, covering her face with her hands. After a few moments, she stood up abruptly. 

“Excuse me, I have to use the restroom.” she mumbled, hiding her face. She started to walk away, but her knee seemed to give out. She caught the back of Jace’s chair, straightened up, and practically limped away. 

Jace and Alec got up to go after her, but Maryse stopped them. 

“Both of you, sit down, now.” 

Against both of their better judgement, they complied. 

“What just happened? Is something going on with Isabelle?” Maryse interrogated. 

Jace spoke first. “I honestly don’t know. Alec and I have noticed her acting differently,” Jace turned to look at him and Alec nodded furiously in agreement. 

“I’m not sure what’s going on, but yeah, she’s been acting strangely.” he reported, a bit guiltily. 

Robert and Maryse exchanged glances. 

“What do you think is going on?” their father asked. 

“I… I don’t know.” Alec replied. 

Silence fell over the table. 

After a few minutes, Isabelle returned, looking better, but she flinched as she sat down, barely suppressing a small groan, but Alec heard it. 

“Isabelle,” Maryse began sharply, not wasting any time. “What’s wrong with you? Alec and Jace mentioned that you’ve been acting strangely.”

Izzy stared straight at Maryse, refusing to look at her brothers. 

“I’m fine, mom. I’ve just been a bit sick. I think I must’ve caught the stomach flu a week ago and I’m still recovering from it, that’s all.” she said smoothly. 

Alec and Jace stared at her because they both knew that was a lie. 

Izzy hadn’t caught the stomach flu, that much was obvious, but they didn’t speak up. Alec decided it would be best to question her about it later, away from their parents. 

The night continued without another incident. 

\---

As the three of them walked back to the subway, Alec swore Izzy was gripping his arm a lot tighter than usual. 

“So, Izzy.” he began. 

“Alec, please, I’m tired. Can we talk about this tomorrow?” Izzy griped, the exhaustion so clear in her voice that Alec felt his heart ache. 

He let it go. 

Jace sent him a withering look and Alec knew that they were both at a loss on what to do. 

When they got home, Izzy kissed Alec goodnight and thanked him. She locked herself in her room and didn’t come out again.

Alec decided it was time to get answers on his own. 

 

**Notes for the Chapter:**

> this chapter mainly sets things up for the next chapter which should be out next week
> 
> I hope you liked it!  
> Comments are always appreciated and welcomed,  
> I love hearing your thoughts - hit me up on tumblr: unorthodoxpartofyourworld


	3. Chapter 3

**Summary for the Chapter:**

> Alec follows Isabelle to the doctor's office and discovers what's been going on. The Lightwood siblings bond <3

**Notes for the Chapter:**

> Hiya~  
> Finally, we find out what's been going on.  
> A few quick notes about this chapter:  
> 1) a lot of you have expressed frustration and Izzy's secretive behavior and you get to see her thought process in this chapter. From the way the show depicts their relationship, Maryse is really cold and critical of Izzy and I believe that there's a lot of emotional abuse in that relationship. Isabelle is one of my favorite characters and when you pay attention to her scenes - hell yes she's a strong independent woman, but you can definitely see signs and traces of emotional abuse in the past and I think that's due to Maryse. In this story, Isabelle has been emotionally abused by Maryse for most of her childhood and a lot of that is part of the reason she hides her illness  
> 2) There's not a lot of malec in this chapter - like i've mentioned before, the beginning of this story is a lot more focused on the Lightwood siblings and their family dynamic. 
> 
> Hit me up on tumblr: unorthodoxpartofyourworld  
> I love hearing your thoughts!  
> Hope y'all enjoy

The next morning, Alec called in sick. He almost never took a day off, so he knew he would be fine. He got dressed and sent a text to Izzy.

_Got called in early. We need to talk when I get home. I love you._

He felt bad about what he was doing, but he was sick of Izzy hiding things from him. He was going to get to the bottom of this _today_.

He listened to Isabelle wake up and pad to the bathroom, groaning softly as she moved through the house. He didn’t want her to know that he was still home, so he sat as silently as possible in his room, barely breathing.

After an hour of listening to her make breakfast and get ready, Alec was close to drifting off, but the sound of Izzy’s voice brought him back, rapt with attention.

“Hello? Yes, I was wondering if Dr. Bane was in today?”

 _Bane…_ Where had he heard that name before? Alec wasn’t sure, but the name sounded eerily familiar, he just couldn’t place it.

“Yeah, Isabelle Lightwood. I know I don’t have an appointment, but I was hoping I could make one? No, for today. Honestly, the sooner the better.” Izzy was saying.

“No, you don’t understand. I can’t wait and I don’t want to go to the hospital. Dr. Bane will know, can you put him on the phone?” Izzy’s voice sounded frustrated, getting louder with every word. “No, it’s not an emergency, but - “ she cut off and Alec could imagine her eyeroll.

“No, I want to speak to him. I’ve been his patient for eight months, he knows my case better than anyone. No, you know what, you listen to me. Just go tell him right now, just tell him my name. Then see if he has the time.” Izzy demanded.

There was a pause and Isabelle let out a loud sigh.

“What did I say?” the victory was clear in her voice. “Right now? Yeah, that works, I can be there in 15 minutes. Thank you, bye.” Izzy finished.

Alec couldn’t believe what he’d just heard.

_Izzy was sick._

Izzy had been sick for almost a year and she was hiding it from him - from everyone.

Alec forced himself not to jump to conclusions, but everything made a little more sense now - the weight loss, the mood swings, the exhaustion, the _health insurance argument._ He felt like a fool for not putting the pieces together sooner.

Alec prayed it wasn’t something terminal or chronic, keeping the ‘c’ word firmly out of his mind.

He listened as Izzy left the house. As soon as the door shut, Alec let out a loud sigh. He pressed the heels of his hands into his eyes and felt anger rise up in him like a wave. Anger at Izzy for hiding this, at their parents, at _Jace,_ even, but mostly, he was angry at himself for not noticing and not doing anything about this sooner.

Alec wanted this to end today.

He picked up his jacket and marched outside, catching a glimpse of Isabelle’s dark waves heading down the stairs of the subway.

He followed.

\---

Isabelle Lightwood was not a fool.

She knew that she couldn’t hide her disease for much longer, but she didn’t expect her treatment to take so long. Eight months ago, when she was first diagnosed, they’d told her that treatment could take anywhere from six months to a year, but assured her that with a case like hers, she should be in and out quickly.

Since her results had been generally positive, she didn’t see any reason to worry her family. Her parents were difficult to deal with and she honestly wasn’t sure how they would take it. It was entirely possible for them to turn it around and somehow blame her for the whole thing, but a part of her had hoped that they’d be caring and sympathetic. She didn’t want to risk it though, they were always a wild card.

She didn’t want to tell her friends because she didn’t want to burden any of them. They were all so happy and excited, she couldn’t bear to bring them down with news about an illness that wouldn’t even matter in six months. If she was being honest with herself, she didn’t want anyone to change the way they behaved with her. She was strong and she didn’t need to bring anyone into her issues - she could deal with them alone.

Izzy pushed her headphones into her ears and leaned her head back as the train she was on started moving.

She did feel bad about lying to Jace and Alec, though. She’d wanted to tell them so many times, but they were both doing so well. Jace was finally in a real relationship - he was in love, she could tell just by looking at him. He was so happy. He’d moved in with Clary and they were happy together. The last thing Izzy wanted to do was throw a wrench in their happiness, especially when it was something she knew she could handle by herself.

Alec was no different. Izzy loved her big brother more than anyone else in the world, which is why she didn’t want to tell him. She knew that if she told him about her disease, it would weigh down on him. He was so happy with his new job and he was finally free from their parents - for the most part. Izzy just wanted to see him happy.

She didn’t want anyone to be weighed down by her. This was her burden to bear.

 _In a few months, it’ll all be fine. It’ll be like this never happened and everything will go back to normal,_ she assured herself.

When her stop came, she stood up, a bit shakily, and walked off the train with her head held high.

She didn’t notice the black-haired man rush off behind her.

When Izzy got to the stairs, she paused, gathering her strength. Her muscles had been failing her a lot more than usual and she wasn’t entirely sure if she _could_ make it all the way. Still, she knew that there wasn’t really another option, so she steeled herself and gripped the railing like a lifeline, pushing herself up the stairs. About halfway up, her knees felt weak and her heart started stuttering.

 _Fuck_ , Izzy thought. This wasn’t good. She’d learned her limits and she knew that if she continued pushing, there was a really good chance that her legs would completely give out.

Groaning, she stopped and leaned against the railing, ignoring the looks she was getting from the busy New Yorkers rushing past her. She rested her hands on her knees and slowly massaged her joints, practicing the deep breathing that her doctor had shown her. After a few minutes, she leaned back and stretched her right leg out, extending it fully and holding it there for 15 seconds. She brought her leg back, rolling her ankle around a few times, and did the same thing to her left leg. After a few more minutes, she felt the muscles in her legs contract and loosen, just a bit.

Izzy gathered her strength and half-dragged herself to the top of the staircase, gasping in relief when she reached the top.

 _I’m so fucking lucky that the office isn’t too far from here,_ Izzy thought to herself, breathing hard as she limped across the street to the rustic, brick building.

When she got there, she collapsed into a chair, breathing heavily from the exertion of the trip there.

“Isabelle? Izzy!” Izzy looked up and she relaxed with a smile as she saw Dr. Catarina Loss rush towards her. Catarina wasn’t Izzy’s doctor, but she often stepped in to consult on her case since she was one of Magnus’ best friends. Magnus Bane was her doctor and Magnus, Catarina, and their friend, Ragnor Fell, ran the clinic together.

Catarina rushed to her side and ordered a few nurses to help bring Izzy into a patient room. Once Izzy was lying down on a bed, Catarina relaxed a bit, bringing her some water and a few aspirin. Izzy thanked her and accepted them gratefully.

“Isabelle, I can only imagine what brings you in today. Magnus is just finishing up with his last patient. He’ll be here in a bit.” Catarina smiled, helping Izzy sit up properly.

“Thank you, Cat. Isn’t it your break right now? Go, I’m fine.” Izzy insisted.

“I am taking my break,” Catarina smirked, pulling up a chair and sitting down in front of Isabelle. “I’m chatting with a dear friend while she waits for her doctor to come in.

“Thank you, Catarina.” Izzy said softly, focusing on keeping her breathing steady.

Catarina started chatting about her day, telling a story about a child who had come in to get a vaccine and had cried so hard in fear that she didn’t even notice the shot. By the time the child was “ready” for her shot, Catarina was already putting on a bandaid - a Pokemon bandaid, just like the little girl had wanted.

Izzy laughed, enjoying the company of someone who knew about her disease and still treated her normally. She let the easy words wash over her and closed her eyes, the serenity of the moment soothing the palpitations of her heart.

There was a soft knock at the door and Izzy was pleased to see her doctor, Magnus Bane, poke his head through the door.

“Everybody decent? Am I interrupting some sacred girl-time?” he called playfully.

“Magnus, you know our sacred girl time wouldn’t be complete without you. You’re the most fashionable out of us all.” Isabelle laughed and waved to Catarina as she slipped out of the room.

“Darling, I’d have to disagree with that - you definitely give me a run for my money, you fashionista.” Magnus grinned, flipping through her file. He came to stand in front of Isabelle and placed his hands on her neck, feeling for stiffness and lumps. “How are you doing?” he asked, eyes full of compassion and concern.

“I’m okay,” she swallowed. “I just, it’s been getting bad, Magnus. I-I don’t understand why the symptoms aren't going away.” Izzy’s face fell.

“Okay, let’s take a look at the rash, shall we?” Magnus handed Isabelle a robe and turned around as she quickly shrugged out of her sweater, pulled the paper gown around her upper body, and laid down on her stomach.

“Ready.” she called.

Magnus turned around stepped forward to inspect her back, but was interrupted by loud shouting from the other side of the door.

“What the hell?” he murmured, just as the door crashed open and he met the eyes of one very frantic Alec Lightwood.

\---

By the time Alec reached the office, he was out of his mind with worry. He had watched Izzy struggle up the stairs and practically limp to the doctor’s office. He’d wanted so badly to rush to her aid and help, but he knew that she would brush it off and then he’d never know what was really going on. It was a tough call, but he figured it would be worth it when he finally discovered what was going on.

Alec rushed in, but his sister was nowhere to be seen. He tried to play it casual at first, sitting in one of the chairs and observing his surroundings. He didn’t see anyone he recognized, so he got up and went to the front desk, asking for Dr. Bane.

“Do you have an appointment?” the receptionist asked in a no-nonsense tone.

“N-No,” Alec stammered. “But my sister, Isabelle Lightwood, she does.” Alec smiled his most charming smile. “I just parked the car, I drove her here. Which room is she in?”

“Isabelle Lightwood?” the receptionist raised an eyebrow, giving him a once over. “She’s 22. If she wanted you in there with her, I’m sure she would’ve let me know. We take our patients privacy very seriously, Mr…”

“Lightwood. I’m her _brother_.” Alec stressed. “I need to be in there with her. She’s… she’s not doing so well right now.” Alec growled, anger coiling in his stomach. He knew that his sister needed him.

The receptionist opened her mouth and began to say something, but instead, Alec’s attention was caught by a nurse who’d come to drop off a file.

“Can you page Dr. Bane and tell him that his next patient is in exam room C? Isabelle Lightwood.” the dark-skinned nurse reported, dropping the file into a metal basket and headed back. Alec rushed behind her and caught the door just before it closed.

“Hey, you can’t do that!” the receptionist protested, getting out of her seat.

Alec ignored her and slipped through the door, eyes wide and frantic as the receptionist click-clacked towards him in here little heels. He moved quickly, eyes frantically canning the rooms until he landed on the one he was looking for.

_Exam Room C_

Alec charged at the door, the receptionist and two nurses now at his heels, and pushed the door open.

\---

Alec pushed the door open and came face to face with Magnus, Isabelle’s friend from last night. He was confused at first, but then he noticed the white lab coat resting over the other man’s clothes and the startled face of his sister looking up at him from the examination table.

Alec opened his mouth but words wouldn’t come out as his eyes landed on his sister’s bare back, a large, circular rash spreading across her inflamed, angry skin. The rash was bruised, broken in places, and there were specks of dried blood clinging to her back.

At that moment, the nurse and receptionist finally caught up to him.

“Dr. Bane! I’m so sorry, this man, he just - well, he just charged in! My apologies, it was m-” the receptionist blabbered, but Magnus simply waved her away with a gentle smile.

“It’s okay, Kara. Please go back to your desk. I can handle this. Thank you, Kara, Jenna.” the doctor dismissed and the two ladies nodded respectfully, turned around, and left.

Alec marched over to Isabelle, inspecting her with a keen eye.

He couldn’t remember the last time she’d worn one of her backless outfits. He felt like that should’ve set something off because Izzy loved her backless dresses and jumpers.

“Alec,” Isabelle began, sitting up slowly. “What are you doing here?” her eyes were wide with fear as she clutched her paper gown tighter around herself.

“Isabelle, I think that maybe it’s time to-” Magnus began, but Alec quickly cut him off.

“What the fuck do you mean, Izzy? You-you’re _sick_. How could you not tell me?” Alec spluttered, hurt coloring his words. “Do you - did I do something, Iz? Is there a reason you didn’t tell me?” he leaned forward and took his little sister’s - his precious baby sister’s - face between his hands, watching the guilt and sadness coil in her eyes.

“Alec, I… I just didn’t want you to worry, big brother.” Izzy gave him a small, guilty smile. “This isn’t a big deal. It was supposed to be over in a few months, but there were, um, some… complications” Izzy explained, her face darkening.

“C-complications? Wha-What’s going on, Izzy?” Alec looked between Izzy and Magnus, fear rising in his stomach.

“Alexander, I think you should sit down.” Magnus said gently, reaching for a chair.

“No, I want to stay right here.” Alec insisted, looping his arms around his sister and holding her close.

“Alec, I love you, big brother, and I’m sorry for keeping this from you. I just didn’t want you to worry.” Izzy explained. She scooted over on the bed, making room for Alec to hop up and sit next to her.

“Izzy, I love you too. Will you please tell me what’s going on?” Alec persisted, and Isabelle sighed, taking her big brother’s hand in hers.

“Alec, I have Lyme’s disease.” Izzy confessed, big brown eyes staring up at Alec’s hazel ones.

A moment passed in silence as Alec wracked his brain for any knowledge whatsoever on _Lyme’s disease_.

“What’s Lyme’s disease?” he asked, finally.

“I, um.” Isabelle turned to Magnus, who stepped in smoothly.

“Alexander, Lyme’s disease is a curable disease that’s originally found in animals, but it’s passed on to humans through ticks. Because it’s not normally found in humans, it can affect the body in a lot of different ways. In Isabelle’s case, it has been affecting her muscles and joints, as well as her nervous and cardiovascular system. The tick itself is easy to remove - that’s what the scar on Isabelle’s back is from. The rash is one of the symptoms. We’ve actually removed the tick from Isabelle’s body about four months ago. All we’re doing now is treating the symptoms until the pathogen leaves her bloodstream.” Magnus explained professionally, showing Alec diagrams of Isabelle’s bloodwork and test results.

Alec nodded, finally getting a sense of what was going on.

“So, this is going to be over soon?” Alec asked, looking at Magnus, who shot Isabelle a look.

“Um, yeah, it was supposed to be over sooner than this, actually.” Izzy began sheepishly. “Remember when I said that there were some complications?”

“What complications?” Alec felt dread coil in his stomach as he looked between the doctor and his sister.

“Your sister… well, the post-treatment symptoms are more aggressive than usual.” Magnus answered carefully.

Alec was getting sick of tip-toeing around the main topic.

“Can someone just please tell me what the hell is going on with _my sister_?” he burst out in frustration, turning a glare on Magnus, who had a sad look on his face.

“Alec, stop.” Isabelle ran a comforting hand between her brother’s shoulder blades, rubbing softly in circles. “I - you can tell him, Magnus.” Izzy said, turning to Magnus.

“You sure?” Magnus asked.

“Of course, why wouldn’t she want to tell me?” Alec all but growled.

“It’s nothing like that, Alexander. I just want to make sure that she feels comfortable. It is her health, after all.” Magnus explained, pulling out a different manilla folder.

Alec understood what Magnus meant, but he still felt irrational anger at the doctor. Alec knew that he should’ve been beyond grateful to Magnus, but he was still angry - angry at the situation, at the disease, at his sister for hiding it - and he had no place to express it, so he directed it at the doctor. Alec knew it wasn’t right, but he couldn’t help it.

Magnus seemed unperturbed at Alec’s hostility, opening the folder and holding it up to show Alec and Isabelle.

“Isabelle came into our offices about six months ago, recommended to me by one of my colleagues, Dr. Raphael Santiago, who works in the Brooklyn General Hospital. She was showing signs of Lou Gehrig’s disease, also known as ALS. After a few initial tests, we found that her bloodwork was inconsistent with ALS, so we looked for other causes - that’s when we found the tick. The problem with Lyme’s disease is that it mimics the symptoms of other diseases and only has a few distinct symptoms that differentiate it. One of those symptoms is the circular rash you see on Isabelle’s back.” Magnus pointed to the red, inflamed skin on Izzy’s back and Alec nodded in understanding. “The-”

“Well, can’t she be treated? What’s the procedure for this?” Alec interrupted.

“Yes, Alexander, I was just getting to that. Isabelle has been treated with antibiotics and the treatment was successful - the infection itself is gone, which is very good, I assure you.” Magnus continued.

“But…?” Alec was getting impatient again.

“But, Lyme is tricky. Although the infection is gone, the pathogen is still active in her bloodstream and we need to flush it out, which is proving to be difficult. What Isabelle is experiencing now is referred to as ‘post-treatment symptoms’, which are fairly common in Lyme patients. It’s not a reason to worry, but she does need to continue treatment because the pathogen is still affecting her.” Magnus finished, placing his hand on Izzy’s shoulder.

“Alec, I thought this was open and shut, I didn’t think there would be complications. I’m sorry, brother, I didn’t mean - “ Isabelle began, squeezing her older brother’s hand.

“So, what happens now? I-is it fatal?” Alec cut her off.

“No, not at this stage. But there is the possibility that it could become chronic.” Magnus answered, looking Alec square in the eye.

Alec buried his head in his hands, finding it difficult to process the whole situation.

“Alexander, if you need a minute -” Magnus began, but Alec cut him off sharply.

“Stop calling me that! You don’t know me, so stop talking to me like you do.” he seethed, drowning in anger and frustration.

Magnus inhaled deeply and chewed on his bottom lip, watching the young man with sympathetic eyes.

“I’ll step outside for a minute, then. Isabelle, come get me when you’re ready, alright?” Magnus turned, hand on the door handle.

“Yes, of course. Magnus, thank you.” Izzy said gratefully.

Magnus nodded graciously and stepped out of the room.

\---

“Alec - “ Izzy began, desperately trying to reach out to her brother.

“Don’t, Izzy. Just stop.” Alec pulled away and hopped off the bed, running his hands through his hair. “How… just what did you think you were doing?” Alec questioned furiously, pacing in the small examination room.

“I thought it wasn’t that big of a deal. It was supposed to be an easy procedure, I just, I didn’t expect this.” Isabelle replied, playing with the fraying edges of her hair nervously.

“How could you think that this wasn’t a big deal? Are you under some kind of illusion that _I don’t care about you_?” Alec thundered, a swirl of emotions ravaging him.

“Of course not! Alec, I just didn’t want to worry you. I didn’t want to worry anyone! I’m my own burden to bear!” Izzy exclaimed.

“Stop it. You take that back right now.” Alec hissed sharply. He understood a bit better now.

Ever since they were kids, Maryse was always tough on Izzy. Whenever Izzy cried, Maryse would shut her down, telling her _big girls don’t cry, Isabelle_. When Izzy was being bullied back in elementary school, Maryse scoffed and told Izzy to stand up for herself, to stop being a weakling. When Izzy needed help with her homework, Maryse chided her for not studying hard enough, not paying enough attention.

Whenever Izzy had a problem, Maryse told her to face it like a Lightwood - head on. Alec remembered the words like it was just the other day.

“Isabelle, you are a Lightwood. Stop passing your problems off to others. You need to learn how to be strong and face your problems like a woman. You are my daughter and I expect you to behave as such. Do not become anyone's _burden_ , Isabelle.”

Alec thought that Izzy had brushed it off - she’d certainly acted like it, storming off to her room after sniping back - but it seemed like years of their mother’s verbal assaults had impacted Izzy more than she let on.

“Izzy,” Alec moved in front of his sister and pulled her in for a hug. “You are not a burden. You will never be a burden. I know that mom used to say all kinds of shit to you, but remember that we are always here for you. Hell, we _want_ to be there for you. Izzy, I love you. It hurts me more when you hide things from me. I don’t want you to go through things alone. I’m your big brother and it’s my job to protect you and be there for you. Will you let me do my job?” Alec murmured into her hair, holding his frail baby sister close.

He felt a wetness on his shirt and he knew that Izzy was crying. He held her tight as her shoulders shook.

“Thank you, big brother.”

**Author's Note:**

> Expect updates weekly, but if I take too long, i'll probably post like 3 times in one week to make up for it #guiltwriting, issa thing.
> 
> this chapter is short but boy are y'all in for a ride after this one


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